where the water had been disturbed.
The two men stared at the scene for long moments. Their eyes, flickering over the scene, picked out more details. Many of the bodies had been dismembered; their bony arms and legs ended in shattered bone, and here and there whole torsos had been cut in half. Ribcages ended in severed spines. Skulls, looking up at the cage with empty eye sockets, had gaping fissures, as if a huge axe had cut through them.
Not all the remains were human; here and there, the large forms of mining robots were piled with the dead. The robots’ steel bodies were riddled with small dents and holes, and the unmistakeable black peppering of shotgun rounds fired at close range.
‘Oh, no,’ Matt whispered.
In a sliding rush of dread that was colder than the deep water that lay below him, he realised what had killed the people in the mine. He remained rooted to the spot, staring into the water, unable to tear his eyes off the scene, as the reality of what had happened washed over him.
When the depressurisation failed to kill everyone in the mine, when the survivors had taken refuge behind secure pressure doors, another terror had been unleashed in the mine. An enemy that could tear its way through steel doors, that could rip and crush, that would walk unblinking into the hail of small arms fire that were the mine personnel’s only defence.
How they had done it, Matt couldn’t begin to guess; it was supposed to be impossible, the protocols were burned in at the hardware level and couldn’t be subverted by software. But PMI had done it somehow; the evidence was staring back at him, the cloven, empty skulls and accusing fingers.
They had been reprogrammed to attack and kill, to break open the sealed doors, and turn on their masters.
It had been the robots.
CHAPTER THIRTY-THREE
The cage carrying Dr Elliott and Peter Abrams came to a stop at the top of the raise, and the brakes locked on. Below them, the service raise bored straight down into the mountain, and into the darkness of the mine.
The cage door slid up and the safety gate moved aside, and they stepped out into the upper shaft station. The robot lumbered out after them, carrying its load of air cylinders, and they stood there, uncertain what to do next.
Abrams looked around them. The shaft station looked identical to the one they had left behind, but there were no passages opening onto it. A single pressure door stood in the centre of the opposite wall.
‘Crawford said there was an airlock,’ Elliott said, looking at the door.
‘Yes, and maybe there’s air still in it, but let’s not take any chances. I say we get our helmets on here before we open that door, yes?’
Elliott nodded, and they lifted four air cylinders off the robot’s arms and took turns to load each other’s suit backpack. Both of them had received a thorough course in using a surface spacesuit as part of their training for the mission, and they cross-checked each other’s equipment, taking their time, making sure that their helmets were sealed, the air flow was correct and that the temperature regulation and radios were working.
The rucksacks containing the radio equipment went on top of the two remaining air cylinders that Bob Five carried. Finally, Abrams was satisfied that they were ready to move out.
‘Okay, let’s open the inner door.’ His voice sounded strange inside his helmet. ‘Bob Five, can you hear me?’
‘YES, MASTER,’ the robot’s deep voice sounded in Abrams’s headset.
‘Okay, follow us.’
Abrams punched the door open button with his gloved hand. The heavy door moved aside a few centimetres before jerking to a halt. For a moment, they thought it had become stuck, but then it slid open, its mechanism making a grating noise.
‘Doesn’t sound too healthy,’ Abrams commented, but stepped through, and Elliott and the robot followed, carrying the air cylinders and radio equipment in its arms. It bent over to pass under the door frame. Its sliding, overlapping joints made it surprisingly flexible for such a large and heavy machine.
Elliott closed the door once the robot was through, and the door moved shut with the same uncertain, scraping motion, and sealed.
The airlock chamber was a white-painted space, about four metres square, cut into the rock, with air ducts and cables in the walls and roof. The outer door was red, with a prominent sign in large white letters:
‘Air okay? Right, here we go.’ Abrams pressed and held the two buttons to start the airlock depressurisation sequence. As the air in the chamber vented out into space, the suits stiffened slightly round their bodies, and the airlock status display changed colour, going from a solid green, to blinking green, to blinking red, and finally the solid red of vacuum.
Abrams pressed the button to open the outer door, and it slid aside silently. A faint swirl of dust stirred outside.
They paused at the airlock door, taking in the scene outside.
The opening led out onto the base of a narrow ramp set in a deep cutting. On either side of the exit, the rock walls of the cutting stood three metres above their heads, and the ramp sloped up between the high walls until it emerged into the intense, arc-like glare of sunlight at the end of the cutting.
‘Make sure your visor is on automatic,’ Abrams warned, ‘and don’t look at the Sun when we get out there.’
‘Okay,’ Elliott said, his breath sounding rasping and hollow in his helmet. He checked the wrist console on his suit, and followed Abrams up the ramp, the robot following behind. Its lumbering gait was strangely silent in the vacuum.
The rock walls on either side fell away as they came to the top of the ramp, and suddenly their heads and upper bodies emerged out of shadow and into the brilliant glare of the Sun.
‘Whoah.’ Abrams let out an involuntary cry of surprise as the sunlight smote him in the face. Even at Mercury’s South Pole, the Sun’s radiant energy was intense; it was like walking from an air-conditioned lobby into the full heat of a tropical day. His helmet visor darkened instantly at the first touch of sunlight, and the suit’s cooling unit increased power to compensate for the sudden inrush of heat.
Elliott came up and stood beside him, and surveyed the scene. The robot halted behind them.
‘Jesus.’
They had emerged from the cutting to stand on a levelled area high on Chao Meng-fu’s ramparts, on the spur that thrust out into the crater. A lightweight post-and-wire guard fence ran around the perimeter of the area. Ahead to their left, the Sun glared over the southern peaks of Chao Meng-fu’s crater wall, a mass of terraces, boulder slopes and hills that climbed up into the black sky.
On their right, northwest, a sheer fall plunged into blackness, and an array of repeater antennas pointed down into the crater, providing infill coverage for the radio shadow behind the crater walls. Feeder bundles from the antenna array snaked across the rock into large junction boxes, and from one of these boxes, a set of heavy cables led off alongside a sloping pathway to the left. It wound its way up into the higher peaks, hugging the shadows.
Abrams and Elliott walked over to the right-hand edge and looked out across the crater. From this high vantage point, they could see almost the entire ring of the crater wall. In the sharp relief of the low sunlight, the encircling peaks looked like a ring of small, broken teeth.
Standing there above the sheer drop, they had the impression that they were staring out over a gigantic, bottomless pit, a gateway to a hidden underworld. Only the central peaks broke the illusion; they rose into the sky in the distance, rising up out of nothingness, their steep-sided peaks blazing in the sunlight above the blackness of
